Weighted Average Assumptions used in Determining Fair Value for Options Granted (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule Of Weighted Average Assumptions For Fair Values Of Stock Options [Line Items]
Expected dividend yield	1.72%	1.66%	1.53%
Expected stock volatility	43.00%	44.00%	41.00%
Risk-free interest rate	1.53%	1.55%	3.33%
Expected holding period	7 years 2 months 12 days	7 years 4 months 24 days	7 years 7 months 6 days
Grant date fair value	$ 17.58	$ 15.19	$ 12.49